ENTERPRISE — A low-pressure system off the Pacific Coast is expected to bring relief by week’s end from the blanket of smoke smothering Wallowa County.
According to the Roger Cloutier, lead forecaster at Pendleton’s National Weather Service office, all of the Columbia Gorge, the basin and the adjacent valleys are socked in with smoke from fires raging in Western Oregon. Relief is coming Thursday, Sept. 17 and 18 with wind, rain and possible thunderstorms. Until then, the air quality will be categorized as “unhealthy.”
“The basin and valleys are entrenched under an inversion,” he said. “The winds aloft are not mixing down into lower elevations, so the smoke is trapped.”
The flow aloft is becoming southwesterly, Cloutier said, and is mixing down to higher ridges and peaks allowing smoke to disperse, especially in Redmond, Bend, Prineville and even the higher elevations of the Blue Mountains and the Wallowas. The county’s higher elevations are keeping the air quality to merely “unhealthy,” while Pendleton and La Grande are in the “very unhealthy” range and Hermiston and Kennewick, Wash., are registering as “hazardous.”
The inversion will stay put until Sept. 17. The www.airnow.gov website recommends people with heart or lung disease, older adults, children and teens to avoid strenuous outdoor activities, keep outdoor activities short and to consider moving physical activities indoors or rescheduling them. For those less vulnerable, the website recommends choosing less strenuous activities like walking instead of running and shortening the amount of time outside.
A large, low-pressure system sitting over the Pacific will move inland Sept. 17 and 18 with a deep, southerly flow, Cloutier said, which will bring instability and moisture into Oregon and Washington.
“As the system shifts eastward the smoke will disperse and bring a slight chance of thunderstorms to develop,” he said.
The prediction is for more showers than thunderstorms, Cloutier said, with winds coming from the south, shifting to the west and later the northwest.
“Whatever does form the system will be wet and hopefully will be enough to scour out the smoke,” he said.